don't use String.lowercase on windows (updated extC now ensure correct casing)

common.ml

@@ -232,9 +232,7 @@ let find_file ctx f =
 
 let get_full_path f = try Extc.get_full_path f with _ -> f
 
-let unique_full_path =
-	if Sys.os_type <> "Win32" && Sys.os_type <> "Cygwin" then get_full_path else
-	(fun f -> String.lowercase (String.concat "/" (ExtString.String.nsplit (get_full_path f) "\\")))
+let unique_full_path = get_full_path
 
 (* ------------------------- TIMERS ----------------------------- *)